(a) Field of the Invention
The present invention relates to a power supply apparatus and a driving method thereof.
(b) Description of the Related Art
Recently, renewable energy has been spotlighted due to problems such as environment destruction, resource exhaustion, and the like. The renewable energy includes photovoltaic, wind power, wave power, tidal power, terrestrial heat, and the like, and particularly, a photovoltaic system has been widely used as an apparatus for converting light irradiated from the sun to electric energy.
Such a photovoltaic system includes a solar cell converting light to electric energy and a power supply apparatus converting a voltage output from the solar cell to a desired output voltage. When the photovoltaic system is connected to a grid, the power supply apparatus includes a DC-DC converter boosting a DC voltage to another DC voltage and an inverter converting an output of the DC-DC convert to an AC voltage.
In general, a range of the voltage output from the solar cell is as wide as about 25V to about 60V, and a DC-DC converter that converts a voltage of such a wide range to a high output voltage (e.g., 400V) needs to be designed.
However, when a DC-DC converter is designed to process such a wide range input voltage, efficiency may be deteriorated. Particularly, when an LLC converter is used as the DC-DC converter, efficiency can be increased, but the LLC converter causes an increase of conduction loss, thereby deteriorating efficiency when using a wide input voltage.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.